Peripheral Nerve Injury Neurosurgeon Yoon Seung-Hwan
Anatomy • Connective tissue - major tissue componant - epineurium, perineurium, endoneurium • Nerve tissue - axon, schwann cell
Peripheral Nerve Injury • Acute injury • Chronic injury (entrapment neuropathy)
Neuropraxia • the mildest form, reversible conduction block • loss of function, which persists for hours or days • direct mechanical compression, ischemia, mild burn trauma or stretch
Axontmetic • axon continuity is disrupted • fascicular integrity is maintained • Wallerian degeneration occurs
Neurotmesis • laceration from sharp or blunt forces • the only important consideration is the timing of repair • acute repair or more bluntly lacerated nerves are repaired 3-4 weeks
Factor s for Decision Making • Age • Segment between injury and end organ • Gap of injury • Mechanism of injury • Severity of injury • Presence of pain
Axonal Regeneration • Initial delay to the distal stump : 1-2 week delay • Growth rate 1mm/day, 1 inch/month • Terminal delay several weeks-several months Recovery within 6 weeks good prognosis
Acute Denervation Fibrillation potentials and positive sharp waves
Regeneration Long duration, small amplitude polyphasic motor unit potentials
Diagnosis Clinical Signs • Motor function • Tinel’s sign positive-sensory function negative(after 4-6weeks)-total interruption • Sweating-sympathetic fiber • Sensory function
Tinel’s sign • advancing along the anatomical distribution of the nerve, particularly if it is does so at the expected rate of nerve regeneration, then this provides evidence of ongoing regeneration.
Diagnosis Electrophysiological Tests • EMG • SNAP • SSEP • Intraoperative NAP
Muscle Atrophy • 24 month rule - 2년 이상 지속 시 muscle scar tissue로 대치되기 때문 에 (비가역변화) 회복불가 • Muscle atrophy start : post-injury 1 month peak : 3rd - 4th month • Segment between injury and end organ
Treatment Time of Operation • Open injury Early intervention Delayed intervention • Closed injury Delayed intervention
Early Intervention • Enlarging hematoma/aneurysmal sac • Predisposing to Volkmann’s ischemic contracture • Severe noncausalsic pain SD • Injury to N. in areas of potential entrapment • Simple, clean lacerating injury
Delayed Intervention • 2-3 months after injury • No clinical or substantial recovery • 장점 1. 손상범위를 정확히 알 수 있다. 2. 동반손상의 치유로 감염을 줄인다. 3. Epineurium이 두꺼워져 봉합이 쉽다. 4. 계획수술로 정확한 수술이 가능하다.
Operations • Neurolysis : internal/external • Nerve repair end-to-end repair : epineural/fascicular autologous graft : sural N. • Neurotization intercostal N./accessory N./cervical plexus within 1 year • Muscle and tendon transfer
Nerve Graft # leading cause of failure of nerve graft • Inadequate resection • Distraction of repair site
Postoperative Care • Neurolysis : 수술직후부터 운동시작 • End-to-end repair : 3주 이상 고정 6주까지 서서히 운동 • Graft : 좀 더 일찍 운동 허용 과도한 관절운동은 피한다
Conclusions 1. Immediate primary repair in sharp injuries with suspected transsection of nerve Immediate repair is especially important for brachial plexus and sciatic nerve transsections because delay leads not only to retraction but also to severe scaring Bluntly transsected nerve best repaired after a delay of several weeks. • A focally injured nerve should be explored if no functional return within 8-10 weeks 3. Decision - making as to whether neurolysis or resection & repair in a lesion in gross continuity based on intraoperative electrophysiological evaluation
Conclusions 4. Split repair with usually graft - lesion in continuity가 partial function or undergoing partial regeneration 5. Careful patient selection for operation - 특히 plexus involved 시 6. Nerve anastomosis 의 failure 주원인은 ① inadequate resectin of scarred nerve ends ② nerve suture distration 7. A good end result requiring rehabilitation from onset of treatment. Prevention of disuse, relief of pain, predicting probable end results of operative procedures.
Chronic Injuries of Peripheral Nerves by Entrapment • Pain • Paresthesia • Loss of function
Pathophysiology of Entrapment • Direct compression segmental demyelination wallerian degeneration(distal) • Ischemia swelling of nerve microcompartment SD
Treatment Conservative Tx • Indications not long history mild-moderate, intermittent reversible cause pregnancy, oral contraceptive, endocrine abnormalities(DM…), type writer • Method nonsteroidal anti-inflammatory drugs splint
Treatment Surgical Indications • Failed conservative tx • Typical clinical finding with electrodiagnostic data • Severe sensory loss muscle atrophy motor weakness
Entrapment of Thoracic Outlet • 원 인 - Cervial rib or anomalous transverse process of C7 - Fibromuscular bands or scalene muscle abnomality • 진 단 - X-ray - NCV & EMG - Angiography – vascular anomaly • Tx : Supraclavicular approach - Best op. management
scalene anterior and medius M.
Entrapment of Ulnar Nerve - Cubital tunnel - Guyon’s canal
Motor Deficit of Ulnar Nerve • Bediction posture : clawing of ring & small finger • Froment’s sign : weakness of adductor pollicis, there will be flexion of the interphalangeal joint of the thumb because of substitution of the median innervated flexior pollicus longus for a weak adductor pollicis
Meralgia Paresthesia Lateral femoral cutaneous nerve injury (L1-2)